Embodiments of the present disclosure relate to a nonvolatile memory device, and more particularly, to a nonvolatile memory device including a source line having a three-dimensional (3D).
A nonvolatile memory device is a memory device capable of preserving stored data even when not powered. Various nonvolatile memory devices such as flash memories have been widely used.
Since increases in the degree of integration of a two-dimensional (2D) nonvolatile memory device, in which a single-layered memory cell is formed over a semiconductor substrate, is limited, a 3D nonvolatile memory device, in which a memory cell is formed along a channel layer vertically protruding from the semiconductor substrate, has been developed. 3D nonvolatile memory devices may have a line-shaped channel layer or a U-shaped channel layer. A 3D nonvolatile memory device having a line-shaped channel layer includes a bit line and a source line respectively formed above and below stacked memory cells. A 3D nonvolatile memory device having a U-shaped channel layer includes a bit line and a source line, both of which are disposed over stacked memory cells. Since a 3D nonvolatile memory device having a U-shaped channel layer includes a single-layered selection gate, it may have a higher degree of integration than a 3D nonvolatile memory device having a line-shaped channel layer.
However, a 3D nonvolatile memory device having a U-shaped channel layer is designed to commonly connect individual source lines using a metal line that passes above cells in the direction of a word-line. Therefore, resistance of the metal line is very high, and thus there is a high possibility of bouncing the source lines.